The present invention relates to a non-woven article, to a method for the manufacture thereof, and to an apparatus for implementing the method.
Fire-resistant fibres like mineral, glass or ceramic fibres are presently used for manufacturing mineral felt essentially in two ways.
In one method, as early as during the manufacture of a fibre, the fibre is sucked onto a suction wire to form a web. Fabricated this way, the article has a compact texture and high weights per unit area. This method cannot be applied for manufacturing thinner qualities. Another drawback is the formation of granular and bead-like impurities in the articles. It is not possible to admix bonding fibres in the article and final bonding of the article is effected with adhesives which evaporate at low temperatures and, thus, make the use of such article at high temperatures difficult.
Another presently applied technique is to use a mineral, glass or ceramic fibre for manufacturing a web by means of water, much the same way as manufacturing paper. Although, in this method, it is possible to include other fibres as well, long (over 50 mm) synthetic fibres cannot be employed as composite or bonding fibres. Another major drawback is that, when emerging from a machine, the non-woven web is wet and especially thick qualities require high-powered drying, resulting in a less economic production line. Also in this method, the final bonding for providing a firm article can only be effected by suing an organic binder with all its above-mentioned drawbacks.
The weight per unit area or the density of articles produced by these methods is quite considerable, which does not allow for optimum ratio of strength to product weight. When using such article as an insulating material, the density of the article bears also significance.